[PATCHv2] x86/purgatory: don't generate debug info for purgatory.ro

[Pingfan Liu]

Purgatory.ro is a standalone binary that is not linked against the rest of
the kernel.  Its image is copied into an array that is linked to the
kernel, and from there kexec relocates it wherever it desires.

Unlike the debug info for vmlinux, which can be used for analyzing crash
such info is useless in purgatory.ro. And discarding them can save about
200K space.

Original:
  259080  kexec-purgatory.o
Stripped debug info:
   29152  kexec-purgatory.o

Signed-off-by: Pingfan Liu <kernelfans at gmail.com>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: Borislav Petkov <bp at alien8.de>
Cc: "H. Peter Anvin" <hpa at zytor.com>
Cc: Hans de Goede <hdegoede at redhat.com>
Cc: Nick Desaulniers <ndesaulniers at google.com>
Cc: Arvind Sankar <nivedita at alum.mit.edu>
Cc: Steve Wahl <steve.wahl at hpe.com>
Cc: linux-kernel at vger.kernel.org
Cc: kexec at lists.infradead.org
To: x86 at kernel.org
---
 arch/x86/purgatory/Makefile | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 088bd76..d24b43a 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -32,7 +32,7 @@ KCOV_INSTRUMENT := n
 # make up the standalone purgatory.ro
 
 PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
-PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss
+PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss -g0
 PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING
 PURGATORY_CFLAGS += $(call cc-option,-fno-stack-protector)
 
@@ -64,6 +64,9 @@ CFLAGS_sha256.o			+= $(PURGATORY_CFLAGS)
 CFLAGS_REMOVE_string.o		+= $(PURGATORY_CFLAGS_REMOVE)
 CFLAGS_string.o			+= $(PURGATORY_CFLAGS)
 
+AFLAGS_REMOVE_setup-x86_$(BITS).o	+= -Wa,-gdwarf-2
+AFLAGS_REMOVE_entry64.o			+= -Wa,-gdwarf-2
+
 $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
 		$(call if_changed,ld)
 
-- 
2.7.5